The present invention relates to a pulp catcher including a substantially horizontally arranged sieve or straining drum located in a container. The depulped juice is removed from the straining drum through a hollow shaft. The outer surface of the straining drum is cleaned by means of a rotating brush roller. Near the bottom of the container there are arranged means for transporting the pulp, for example, by means of a screw or worm to a substantially centrally located outlet pipe.
Several pulp catchers of differing constructions are known in the art. One type of pulp catcher comprises a rotating sieve or straining drum for separating the juice from the pulp proper. This type of pulp catcher requires cleaning means for the straining drum in order to keep the sieve apertures open and for removing the pulp from the surface of the straining drum. Another type of pulp catcher comprises a straining drum which is arranged substantially vertically. In this type of catcher, the straining surface of the drum is cleaned by means of stationary doctor blades which are pressed against the rotating drum. Depending upon the type of operation, that is whether the juice flows from the inside of the drum to the outside thereof or vice versa, the doctor blades are arranged either on the inside or on the outside of the straining drum.
The present invention aims at improving the known type of pulp catchers which comprise a sunstantially horizontally arranged straining drum, wherein the juice flows from the outside of the drum to the inside thereof and wherein the straining drum is cleaned by a rotating brush roller. Compared to the pulp catcher with a stationary doctor blade, the pulp catcher with a rotating brush roller has the advantage that a higher relative motion or speed may be accomplished during the cleaning by rotating the brush roller and the straining drum in opposite directions. Doctor blades have the further disadvantage that a portion of the pulp may be pressed into the sieve apertures of the straining drum whereby the apertures may be clogged for longer periods of time. Contrary thereto a rotating brush roller provides a substantially larger assurance that the sieve apertures of the straining drum will be kept free and unclogged.
However, pulp catchers with rotating brush rollers have the drawback that the rotating brush rollers are subject to a substantial wear and tear. Due to the fact tha the brush rollers in prior art devices are arranged with their rotational axis at a fixed spacing from the straining drum, it cannot be avoided that due to the wear and tear of the brush bristles, the cleaning efficiency is varied. The optimal cleaning efficiency is achieved only during a limited time of operation; namely, subsequently to installing a new brush roller. Subsequent to said limit operational time the disadvantage could not be avoided heretofore, that the sieve of the straining drum is cleaned unsatisfactorily.
It would be possible to assure a continuously satisfactory cleaning of the straining drum by a respectively frequent changing of the brush roller. However, this is uneconomical due to the high consumption of brush rollers. Besides, the exchange of the brush rollers would cause frequent interruptions of the operation because the brush roller can be exchanged only when the pulp catcher is at a standstill.